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monumental architecture

The simplest and cheapest stonework is rubble;
i.e., roughly broken stones of any shape bounded in mortar. The strongest and most suitable stonework for monumental architecture is
ashlar masonry, which consists of regularly cut blocks (usually rectangular). Because of its weight and the precision with which it can be shaped, stone masonry (in contrast with brick) does not depend on...

use in Transcaucasia

Transcaucasia contains some fine church architecture dating from the 4th century
ad onward, including some very early pendentives. Ashlar masonry was used there instead of the bricks more common in Byzantine architecture. The most extensive remains of this kind are in the ruins of the city of Ani (modern Ocaklı) in Turkey, across the border from Armenia.